Glass composition



Patented Apr. 29, 1941 GLASS COMPOSITION Willem Elenbaas and GottfriedBruno Jonas,

Eindhoven, Netherlands No Drawing. Original application July 28, 1936,Serial No. 93,114. Divided and this application April 16, 1938, SerialNo. 202,570. In Germany August 6, 1935 1 Claim.

The present invention relates to glass compositions generally and moreparticularly the invention relates to such compositions useful as acontainer material for gaseous electric discharge devices containing aquantity of chemically active, difiicultly vaporizable metal the vaporof which is light emitting during the operation of the device.

Ionized cadmium vapor is a chemically active material and attacks theglasses customarily used as container glasses for incandescent lamps andgaseous electric discharge lamps containing rare gases, such as lead orlime glasses. Cadmium vapor not only emits visible radiation whenexcited to luminescence by the passage of an electric dischargetherethrough but also emits ultraviolet rays.

The object of the present invention is to provide a visible andultra-violet ray transmitting glass which has a high softeningtemperature and which is resistant to chemical attack by hot, ionizedcadmium vapor. Still further objects of the invention will be apparentto those skilled in the art from the following particular description.

We have discovered that a glass which is chem- Particularly good glassesare those having the following compositions:

I II Ill.

Percent Percent Percent 78 57 55 i 12 23 15 CM 10 30 These glasscompositions are useful as container glasses for gaseous electricdischarge lamp devices generally and particularly for such de viceswhich operate at elevated container temperatures, such as cadmium vapordischarge lamp devices. These glasses are resistant to the hot, ionizedcadmium vapor, have a high softening temperature and transmit thevisible and ultraviolet rays emitted by excited cadmium vapor.Preferably the lamp container consisting of such glass in whole or inpart is an elongated, tubular, sealed one having a thermionic, activatedelectrode mounted therein at each end thereof and having a quantity ofcadmium and a starting gas therein, such as argon, neon or xenon, or amixture of such gases, at a pressure of about 1 to 10 mm. The lampdevice starts as a gas discharge lamp and operates as a vapor dischargelamp. The discharge in the lamp during the operation thereof when thelight emitted thereby is rich in rays characteristic of the cadmiumvapor is an arc discharge of the positive column type.

Preferably the lamp device is mounted in a light transmitting heatconservator, such as a sealed envelope or a Dewar flask to increase theemciency thereof.

This application is a division of our co-pending application SerialNumber 93,114, filed July 28, 1936, now U. S. Patent 2,116,742.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

A glass containing:

Per cent Silica ($102) '78 Alumina (A1203) 12 Calcium oxide (CaO) 10WILLEM ELENBAAS. GOTIFRIED BRUNO JONAS.

Patent no; 2,2Lo,527.

said patent should have bee CERTIFICATE OF CORRECTION.

April 29,- 191 WILLEM ELENBAAS, ET AL.

It is hereby certified that the above numbered pa Willem Elenbaas andGottfried Bruno Jonas, whereas tent was erroneously issued to theinventors,

tion of New York,v {as assig the record of assignments in this office;and that the said Letters Patent should beread with this correctiontherein that the record of the case in the, Patent Office.

Signed and sealed this 22nd day of July, A. D. ,19h1.

Henry Van Arsd'ale,.

(Seal) Acting Commissioner of Patents.

n issued to General Electric Company, a' corpora nee-of the entireinterest therein, as shown by "the same may conform to

